зеркало из https://github.com/github/ruby.git
* math.c (math_gamma): new method Math.gamma.
(math_lgamma): new method Math.lgamma. * include/ruby/missing.h (tgamma): declared unless HAVE_TGAMMA. (lgamma_r): declared unless HAVE_LGAMMA_R. * configure.in (tgamma): check for replacement funtions. (lgamma_r): ditto. * missing/tgamma.c: new file. based on gamma.c from "C-gengo niyoru saishin algorithm jiten" (New Algorithm handbook in C language) (Gijyutsu hyouron sha, Tokyo, 1991) by Haruhiko Okumura. * missing/lgamma_r.c: ditto. * LEGAL (missing/tgamma.c): describe as public domain. (missing/lgamma_r.c): ditto. git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@15388 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
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21
ChangeLog
21
ChangeLog
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@ -1,3 +1,24 @@
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Thu Feb 7 10:39:21 2008 Tanaka Akira <akr@fsij.org>
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* math.c (math_gamma): new method Math.gamma.
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(math_lgamma): new method Math.lgamma.
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* include/ruby/missing.h (tgamma): declared unless HAVE_TGAMMA.
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(lgamma_r): declared unless HAVE_LGAMMA_R.
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* configure.in (tgamma): check for replacement funtions.
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(lgamma_r): ditto.
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* missing/tgamma.c: new file. based on gamma.c from
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"C-gengo niyoru saishin algorithm jiten" (New Algorithm handbook
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in C language) (Gijyutsu hyouron sha, Tokyo, 1991)
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by Haruhiko Okumura.
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* missing/lgamma_r.c: ditto.
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* LEGAL (missing/tgamma.c): describe as public domain.
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(missing/lgamma_r.c): ditto.
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Thu Feb 7 09:05:57 2008 Yukihiro Matsumoto <matz@ruby-lang.org>
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* ext/nkf/nkf-utf8/nkf.c (nkf_enc_from_index): BINARY does not
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2
LEGAL
2
LEGAL
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@ -158,6 +158,8 @@ ext/digest/sha1/sha1.[ch]:
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These files are all under public domain.
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missing/erf.c:
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missing/tgamma.c:
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missing/lgamma_r.c:
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missing/crypt.c:
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missing/vsnprintf.c:
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@ -649,7 +649,8 @@ esac
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AC_FUNC_MEMCMP
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AC_REPLACE_FUNCS(dup2 memmove strerror strftime\
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strchr strstr crypt flock vsnprintf\
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isnan finite isinf hypot acosh erf strlcpy strlcat)
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isnan finite isinf hypot acosh erf tgamma lgamma_r \
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strlcpy strlcat)
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AC_CHECK_FUNCS(fmod killpg wait4 waitpid fork spawnv syscall chroot fsync getcwd eaccess\
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truncate chsize times utimes utimensat fcntl lockf lstat\
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link symlink readlink\
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@ -79,6 +79,14 @@ extern double erf(double);
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extern double erfc(double);
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#endif
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#ifndef HAVE_TGAMMA
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extern double tgamma(double);
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#endif
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#ifndef HAVE_LGAMMA_R
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extern double lgamma_r(double, int *);
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#endif
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#ifndef isinf
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# ifndef HAVE_ISINF
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# if defined(HAVE_FINITE) && defined(HAVE_ISNAN)
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73
math.c
73
math.c
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@ -486,6 +486,76 @@ math_erfc(VALUE obj, VALUE x)
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return DOUBLE2NUM(erfc(RFLOAT_VALUE(x)));
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}
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/*
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* call-seq:
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* Math.gamma(x) => float
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*
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* Calculates the gamma function of x.
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*
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* Note that gamma(n) is same as fact(n-1) for integer n >= 0.
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* However gamma(n) returns float and possibly has error in calculation.
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*
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* def fact(n) (1..n).inject(1) {|r,i| r*i } end
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* 0.upto(25) {|i| p [i, Math.gamma(i+1), fact(i)] }
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* =>
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* [0, 1.0, 1]
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* [1, 1.0, 1]
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* [2, 2.0, 2]
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* [3, 6.0, 6]
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* [4, 24.0, 24]
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* [5, 120.0, 120]
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* [6, 720.0, 720]
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* [7, 5040.0, 5040]
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* [8, 40320.0, 40320]
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* [9, 362880.0, 362880]
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* [10, 3628800.0, 3628800]
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* [11, 39916800.0, 39916800]
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* [12, 479001599.999999, 479001600]
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* [13, 6227020800.00001, 6227020800]
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* [14, 87178291199.9998, 87178291200]
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* [15, 1307674368000.0, 1307674368000]
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* [16, 20922789888000.0, 20922789888000]
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* [17, 3.55687428096001e+14, 355687428096000]
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* [18, 6.40237370572799e+15, 6402373705728000]
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* [19, 1.21645100408832e+17, 121645100408832000]
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* [20, 2.43290200817664e+18, 2432902008176640000]
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* [21, 5.10909421717094e+19, 51090942171709440000]
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* [22, 1.12400072777761e+21, 1124000727777607680000]
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* [23, 2.58520167388851e+22, 25852016738884976640000]
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* [24, 6.20448401733239e+23, 620448401733239439360000]
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* [25, 1.5511210043331e+25, 15511210043330985984000000]
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*
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*/
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static VALUE
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math_gamma(VALUE obj, VALUE x)
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{
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Need_Float(x);
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return DOUBLE2NUM(tgamma(RFLOAT_VALUE(x)));
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}
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/*
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* call-seq:
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* Math.lgamma(x) => [float, -1 or 1]
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*
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* Calculates the logarithmic gamma of x and
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* the sign of gamma of x.
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*
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* Math.lgamma(x) is same as
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* [Math.log(Math.gamma(x)), Math.gamma(x) < 0 ? -1 : 1]
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* but avoid overflow by Math.gamma(x) for large x.
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*/
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static VALUE
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math_lgamma(VALUE obj, VALUE x)
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{
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int sign;
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VALUE v;
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Need_Float(x);
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v = DOUBLE2NUM(lgamma_r(RFLOAT_VALUE(x), &sign));
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return rb_assoc_new(v, INT2FIX(sign));
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}
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/*
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* The <code>Math</code> module contains module functions for basic
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* trigonometric and transcendental functions. See class
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@ -541,4 +611,7 @@ Init_Math(void)
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rb_define_module_function(rb_mMath, "erf", math_erf, 1);
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rb_define_module_function(rb_mMath, "erfc", math_erfc, 1);
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rb_define_module_function(rb_mMath, "gamma", math_gamma, 1);
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rb_define_module_function(rb_mMath, "lgamma", math_lgamma, 1);
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}
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@ -0,0 +1,64 @@
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/* lgamma_r.c - public domain implementation of error function lgamma_r(3m)
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lgamma_r() is based on gamma(). modified by Tanaka Akira.
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reference - Haruhiko Okumura: C-gengo niyoru saishin algorithm jiten
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(New Algorithm handbook in C language) (Gijyutsu hyouron
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sha, Tokyo, 1991) [in Japanese]
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http://oku.edu.mie-u.ac.jp/~okumura/algo/
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*/
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/***********************************************************
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gamma.c -- Gamma function
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***********************************************************/
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#include <math.h>
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#define PI 3.14159265358979324 /* $\pi$ */
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#define LOG_2PI 1.83787706640934548 /* $\log 2\pi$ */
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#define LOG_PI 1.14472988584940017 /* $\log_e \pi$ */
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#define N 8
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#define B0 1 /* Bernoulli numbers */
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#define B1 (-1.0 / 2.0)
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#define B2 ( 1.0 / 6.0)
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#define B4 (-1.0 / 30.0)
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#define B6 ( 1.0 / 42.0)
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#define B8 (-1.0 / 30.0)
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#define B10 ( 5.0 / 66.0)
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#define B12 (-691.0 / 2730.0)
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#define B14 ( 7.0 / 6.0)
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#define B16 (-3617.0 / 510.0)
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static double
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loggamma(double x) /* the natural logarithm of the Gamma function. */
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{
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double v, w;
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v = 1;
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while (x < N) { v *= x; x++; }
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w = 1 / (x * x);
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return ((((((((B16 / (16 * 15)) * w + (B14 / (14 * 13))) * w
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+ (B12 / (12 * 11))) * w + (B10 / (10 * 9))) * w
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+ (B8 / ( 8 * 7))) * w + (B6 / ( 6 * 5))) * w
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+ (B4 / ( 4 * 3))) * w + (B2 / ( 2 * 1))) / x
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+ 0.5 * LOG_2PI - log(v) - x + (x - 0.5) * log(x);
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}
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/* the natural logarithm of the absolute value of the Gamma function */
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double
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lgamma_r(double x, int *signp)
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{
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if (x < 0) {
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double i, f, s;
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f = modf(-x, &i);
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if (f == 0.0) {
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*signp = 1;
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return 1.0/0.0;
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}
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*signp = (fmod(i, 2.0) != 0.0) ? 1 : -1;
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s = sin(PI * x);
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if (s < 0) s = -s;
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return LOG_PI - log(s) - loggamma(1 - x);
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}
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*signp = 1;
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return loggamma(x);
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}
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@ -0,0 +1,49 @@
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/* tgamma.c - public domain implementation of error function tgamma(3m)
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reference - Haruhiko Okumura: C-gengo niyoru saishin algorithm jiten
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(New Algorithm handbook in C language) (Gijyutsu hyouron
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sha, Tokyo, 1991) [in Japanese]
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http://oku.edu.mie-u.ac.jp/~okumura/algo/
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*/
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/***********************************************************
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gamma.c -- Gamma function
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***********************************************************/
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#include <math.h>
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#define PI 3.14159265358979324 /* $\pi$ */
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#define LOG_2PI 1.83787706640934548 /* $\log 2\pi$ */
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#define N 8
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#define B0 1 /* Bernoulli numbers */
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#define B1 (-1.0 / 2.0)
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#define B2 ( 1.0 / 6.0)
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#define B4 (-1.0 / 30.0)
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#define B6 ( 1.0 / 42.0)
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#define B8 (-1.0 / 30.0)
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#define B10 ( 5.0 / 66.0)
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#define B12 (-691.0 / 2730.0)
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#define B14 ( 7.0 / 6.0)
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#define B16 (-3617.0 / 510.0)
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static double
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loggamma(double x) /* the natural logarithm of the Gamma function. */
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{
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double v, w;
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v = 1;
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while (x < N) { v *= x; x++; }
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w = 1 / (x * x);
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return ((((((((B16 / (16 * 15)) * w + (B14 / (14 * 13))) * w
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+ (B12 / (12 * 11))) * w + (B10 / (10 * 9))) * w
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+ (B8 / ( 8 * 7))) * w + (B6 / ( 6 * 5))) * w
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+ (B4 / ( 4 * 3))) * w + (B2 / ( 2 * 1))) / x
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+ 0.5 * LOG_2PI - log(v) - x + (x - 0.5) * log(x);
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}
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double tgamma(double x) /* Gamma function */
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{
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if (x < 0)
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return PI / (sin(PI * x) * exp(loggamma(1 - x)));
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return exp(loggamma(x));
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}
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